The objective of the first part of the experiment was to ferment ethanol from sucrose. The second objective for the following lab session was to utilize simple and fractional distillation of a fermented mixture to obtain ethanol. Graphs were utilized to compare the data collected from both methods and compare the efficiency of simple distillation to fractional distillation methods. Procedure and Observations: Fermentation Set up Procedure Observations Place 20 grams of sucrose into a 250 mL round bottom flask.
Then add 100 mL of deionized water and 1.5 grams of yeast. Stir the solution until all of the sugar has dissolved. 20.001 g of sucrose were weighed out 1.4962 g of yeast were weighed out Add 17-18 mL of Pasteur salts solution to the round bottom flask and swirl to mix. 17.5 mL of Pasteur salts added Cap the flask with a lightly greased glass vacuum adapter to which a length of rubber tubing has been attached.
The set up was secured with rubber bands and clamps to keep it from falling apart Transfer the mixture from the r.b. flask to a large beaker. Use paper towels in between the layers of glass for cushioning. Secured r.b.
flask with paper towels underneath and around sides Next, fill a medium sized test tube about halfway with limewater. Stabilize the test tube in a beaker or Erlenmeyer flask. Submerge the free end of the rubber tubing into the limewater. Used paper towels to secure the test tube as well Leave the set up for a week to allow for fermentation to occur Procedure for Simple Distillation (Fractional Distillation was completed, so no observations were recorded): Transfer 90 mL of your solution to a 250 r.b. flask and set-up for simple distillation. Don’t forget to use a boiling chip and remember to lightly grease all joints.
Use a graduated cylinder as a receiving flask. Distill at a rate of about 1-2 drop/second until the temperature has held steadily between 96-100°C for several minutes OR until about 20 mL of distillate has been collected. Record the temperature as each ~0.5 mL-1.0 mL portion is collected. Using this data, generate a graph showing temperature (y-axis) vs.
volume of distillate (x-axis). Pipet 1.00 mL (or 2.00 mL, depending on which pipet is available) of the simple distillate into a clean, tared (3 decimal places) 10 mL E. flask or beaker. Using the table attached, estimate the ethanol content of your simple distillate from density measurements. Procedure Fractional Distillation Observations Before distilling, add about 5 g of Celite to the fermentation mixture and mix thoroughly. Collect the filtrate via vacuum filtration into a large filter flask 5.031 grams of Celite was added The mixture had a strong odor and was a light brown color Transfer 90 mL of the solution to a 250 mL r.b.
flask. 90.1 mL of filtrate was measured using a graduated cylinder Filtrate was clear with a yellow tint Set up fractional distillation as pictured below making sure to lightly grease all joints. Use a graduated cylinder for a receiving flask. Utilize glass beads as packing for the column.
Heat the solution to boiling and then moderate the heating so that the condensate moves slowly up the fractioning column. Foil was placed around the top of the round bottom flask to assist in heating the mixture Gradually increase the temperature as distillation proceeds in order to maintain a rate of approximately 1 drop every 2-3 seconds. Drops occurred in 3-4 at a time and then had a pause before more drops came down the column Three fractions of distillate should be obtained in separate labeled Erlenmeyer flasks. Volume and temperature readings are charted below The first fraction collected is the distillate produced between temperatures 77-80°C The second fraction is between 80-96°C. The final fraction is collected above 96°C First fraction was small.
Second fraction was the largest. Record volume and temperature per every 0.5 to 1 mL of liquid collected in the graduated cylinder. Distill the liquid until 100°C has been reached Removed the graduated cylinder when temperature reached 100°C Use a volumetric pipet to measure 1 mL of distillate into a 10 mL beaker. Weigh the liquid and compare the density to the chart provided to find the percent ethanol. Find density of all three fractions obtained.
Fermentation Setup Simple and Fractional Distillation Setup Results: Simple Distillation Volume distillate (mL) Temperature (°C) 2 78.2 4 78.7 6 79.3 8 81.2 10 82.9 12 84.1 14 84.8 Volume (mL) 5 mL Weight (g) 4.518 Density (g/mL) 0.9036 % Ethanol by weight 56.0 % Ethanol by volume 63.8 Fractional Distillation Fractions Volume (mL) Temperature (°C) First 0 75.0 1.0 76.5 2.0 78.0 3.0 78.8 4.0 79.1 5.0 79.7 6.0 80.4 7.0 80.4 8.0 80.6 9.0 80.9 10.0 80.9 Second 1.0 81.1 2.0 83.6 2.5 84.9 3.0 86.3 3.5 89.2 4.0 92.0 4.5 93.2 5.0 95.9 Third 1.0 96.1 1.5 97.4 2.0 98.2 2.5 98.7 3.0 99.1 3.5 99.7 4.0 100.2 Fraction 1 Fraction 2 Fraction 3 Volume (mL) 2.0 mL 2.0 mL 2.0 mL Weight (g) 1.73 g 1.87 g 2.09 g Density (g/mL) 0.8650 g/mL 0.9350 g/mL 0.9569 g/mL % Ethanol by weight 70.0 40.0 30.2 % Ethanol by volume 76.9 47.3 36.4
